Claressa Shields rose from poverty and obscurity to celebrity by winning gold at the 2012 Olympics in London.

I am sitting in a small conference room in the Hilton in downtown Austin, one of the official sites of this year's South by Southwest festival. Across from me is US Olympic gold medalist boxer Claressa Shields, her first trainer, Jason Crutchfield, and the directors of a new documentary about Shields, T-Rex, Drea Cooper and Zackary Canepari. The night before, the group had attended the world premiere of the film as part of the festival and are now gathered to do a stream of interviews. Time is tight, publicists are hovering. But the group is laughing, and their words thoughtful and honest.

For anyone who has seen the film (and you should see the film) or has seen Shields in interviews, that mixture of lightheartedness and smart frankness will not come as a surprise. Shields is known for both, and they explain her charm, evident on screen and in person.

The film chronicles Shields' life during the run up to the 2012 Olympics, the games themselves, and a few months afterward. Then 17, now 20, the middleweight dominated the Olympic trials and then battled her way to gold against bigger, more experienced fighters. But upon returning to real life, she struggled to capitalize on her victory, and ultimately her failure to secure endorsements.

T-Rex is unflinching, showing the reality of growing up poor and black in Flint, Michigan. Shields' sister talks about her hopes that Claressa will hit the big time and take her out of there. We learn about their mother's abusive behavior, about poverty, about the rash of teen pregnancy in Shields' community ("Girls get easily pregnant in Flint," Shields says). But we also see Claressa on her seventeenth birthday getting cake smashed in her face and doing foot races in the street with her friends, see her shaving her legs while skyping with Crutchfield before a fight at Olympic qualifying in China, going to prom with a boy she is in love with, and graduating from high school. Claressa told me that after seeing the documentary, "when I think back at the past, and I look at and see our journey, I was like, 'Wow. It was great. It was a lot of fun.'"

The lack of endorsements is a sore point, though. "The way she came onto the scene, it was like BAM!," Crutchfield says. "In one year. But it was really four years worth of work with her. But within one year, when she got into the senior division, she just took everything. I thought people would jump on that. It didn't happen. It just didn't happen." Shields started training with Crutchfield at his gym when she 11. "I trained my whole life for the Olympics," she says. "I didn't have a childhood, I really couldn't go to the beach with my friends. Couldn't go to parties. Just training, training, training."

In the film, post-Olympics, Shields and Crutchfield meet with representatives from USA boxing to discuss what she needs to do to improve her image in order to secure sponsors. After the people from USA boxing suggest that she stop saying publicly that she enjoys beating people up and making them cry, Claressa looks at them confused and says simply, "I box." When I ask her what she now says whenever someone asks why she enjoys this sport, she leans back and replies, "I just say that I love to compete or love to test the results of training. But then sometimes it just slips and I do say it. I just love boxing. Train to get there and to just fight somebody." The point of the sport, she says, is "to get into there to beat this person up." Crutchfield then interjects, laughing as he begins his own story about Shields. "One time, I said, 'what really makes you want to box? what do you really like, what do you love about it?' And she said, 'hmmm. I love making those little girls cry.' She was like 13 or 14." Crutchfield rolls around in his seat, his body shaking with laughter. The entire conference room joins in.

Shields says that "with no endorsements I was like, what did I do it for? I just blocked it out. You got to adjust to how your life is." Things are a bit easier these days, at least. "I get money from USA boxing now, a lot more money than I was getting," she says. "I don't have to go without meals anymore. I just live with that and planning for 2016 and hopefully things turn out different." When Canepari confirms that the amount of money is now enough for basic support, Shields agrees but then adds, "Yeah, but I'm a celebrity, though."

The run up to 2016 will be different than the one from 2012, namely in that Crutchfield is no longer her trainer. In the film, Crutchfield, who used to be a fighter himself, says, "A coach always wants a champion. Believe me. That's why we coach. I just never thought it was going to be a girl." In both the documentary and in person, Shields heaps praise on Crutchfield. In the movie, she says, "Without Jason, there wouldn't be no gold medal." Now years later in the hotel conference room, when I ask her why she is such a good boxer, she tells me, "Because of my trainer," and points to him, their shoulders touching, him looking straight ahead at the opposite wall. "I've always had heart to get in there and fight. I was taught everything I knew. I was taught how to jab, why to do this, and why not to do that. I was taught that. From 11 years old, every day in the gym. Every. Day. He taught me a lot more than boxing, taught me a lot of things outside the ring. Just about life period."

Shields preparing for the London Olympics. Photo by John David Mercer-USA TODAY Sports

It is unclear exactly why Crutchfield no longer coaches her. When I ask if she now works with USA boxing, Shields shrugs and says, "Eh." Then she laughs and adds, "something like that."

Crutchfield, for his part, says that Shields is a great boxer because "she's gifted." Beyond her physical capabilities (he calls her speed "a gift"), he says, "as far as her heart, her determination, I've never seen a female like that. Never. And even some of the guys. She's blessed. She's blessed. Yes, she is."

Shields tells me her mental game is very important overall. "A lot of [the women] who I fought have been way stronger than me, a lot more experienced than me," she says. "But it's just that mental thing of thing of not ever giving up, keep fighting when you are tired, knowing you have trained hard enough and are prepared for the situation."

It's not hard to extrapolate out and see how that applies to so much of her life. At the end of T-Rex, Shields says, "I'm 19. My life don't end here. As long as I'm boxing, I'm going to be ok." After seeing this film, learning her story, and meeting her in person, it's hard to argue with that.